Transcatheter valve prosthesis having an external skirt for sealing and preventing paravalvular leakage

ABSTRACT

A transcatheter valve prosthesis including a tubular stent includes an interior skirt or skirt portion is coupled to and covers an inner circumferential surface of the stent, and an exterior skirt or skirt portion is coupled to and covers an outer circumferential surface of the stent. A prosthetic valve component is disposed within and secured to the interior skirt or skirt portion. The interior and exterior skirts or skirt portions may overlap to form a double layer of skirt material on the stent, or may be portions of a skirt that do not overlap such that only a single layer of skirt material covers the stent. When the stent is in at least the compressed configuration, at least one endmost crown may be positioned radially inwards with respect to the remaining endmost crowns formed at the inflow end of the stent in order to accommodate the exterior skirt.

FIELD OF THE INVENTION

The present invention relates in general to transcatheter valveprostheses, and more particularly to a transcatheter valve prosthesishaving one or more components for preventing paravalvular leakage.

BACKGROUND OF THE INVENTION

A human heart includes four heart valves that determine the pathway ofblood flow through the heart: the mitral valve, the tricuspid valve, theaortic valve, and the pulmonary valve. The mitral and tricuspid valvesare atrioventricular valves, which are between the atria and theventricles, while the aortic and pulmonary valves are semilunar valves,which are in the arteries leaving the heart. Ideally, native leaflets ofa heart valve move apart from each other when the valve is in an openposition, and meet or “coapt” when the valve is in a closed position.Problems that may develop with valves include stenosis in which a valvedoes not open properly, and/or insufficiency or regurgitation in which avalve does not close properly. Stenosis and insufficiency may occurconcomitantly in the same valve. The effects of valvular dysfunctionvary, with regurgitation or backflow typically having relatively severephysiological consequences to the patient.

Recently, flexible prosthetic valves supported by stent structures thatcan be delivered percutaneously using a catheter-based delivery systemhave been developed for heart and venous valve replacement. Theseprosthetic valves may include either self-expanding orballoon-expandable stent structures with valve leaflets attached to theinterior of the stent structure. The prosthetic valve can be reduced indiameter, by crimping onto a balloon catheter or by being containedwithin a sheath component of a delivery catheter, and advanced throughthe venous or arterial vasculature. Once the prosthetic valve ispositioned at the treatment site, for instance within an incompetentnative valve, the stent structure may be expanded to hold the prostheticvalve firmly in place. One example of a stented prosthetic valve isdisclosed in U.S. Pat. No. 5,957,949 to Leonhardt et al. entitled“Percutaneous Placement Valve Stent”, which is incorporated by referenceherein in its entirety. Another example of a stented prosthetic valvefor a percutaneous pulmonary valve replacement procedure is described inU.S. Patent Application Publication No. 2003/0199971 A1 and U.S. PatentApplication Publication No. 2003/0199963 A1, both filed by Tower et al.,each of which is incorporated by reference herein in its entirety.

Although transcatheter delivery methods may provide safer and lessinvasive methods for replacing a defective native heart valve, leakagebetween the implanted prosthetic valve and the surrounding native tissuemay occur if not accommodated for by a particular implant. For instance,leakage may occur due to the fact that deployment of a minimallyinvasive cardiac valve is intended to occur without actual physicalremoval of the diseased or injured heart valve. Rather, the replacementstented prosthetic valve is contemplated to be delivered in a compressedcondition to the native valve site, where it is expanded to itsoperational state within the native valve. Calcified or diseased nativeleaflets are to be pressed to the side walls of the native valve by theradial force of the stent frame of the prosthetic valve. However, it hasbeen shown that calcified leaflets do not allow complete conformance ofa stent frame with a native valve and therefore this ill-fit within thenative anatomy may be a source of paravalvular leakage (PVL), assignificant pressure gradients across the implanted prosthetic valve maycause blood to leak through the gaps between the implanted prostheticvalve and the calcified anatomy.

Embodiments hereof are related to transcatheter valve prostheses havingone or more components attached thereto or integrated thereon to addressand prevent paravalvular leakage.

BRIEF SUMMARY OF THE INVENTION

Embodiments hereof relate to a transcatheter valve prosthesis includinga tubular stent having a compressed configuration for delivery within avasculature and an expanded configuration for deployment within a nativeheart valve. The tubular stent includes a plurality of crowns and aplurality of struts with each crown being formed between a pair ofopposing struts, the tubular stent having endmost crowns formed at aninflow end thereof. A skirt is coupled to the tubular stent, with afirst portion of the skirt being attached to and covering an innercircumferential surface of the tubular stent and a second portion of theskirt being attached to and covering an outer circumferential surface ofan inflow end of the tubular stent. The skirt is continuous from thefirst portion to the second portion such that the first and secondportions do not overlap. A prosthetic valve component is disposed withinand secured to the first portion of the skirt. When the tubular stent isin at least the compressed configuration at least one endmost crown ispositioned radially inwards with respect to the remaining endmost crownsformed at the inflow end of the tubular stent.

According to another embodiment hereof, a transcatheter valve prosthesisincludes a tubular stent having a compressed configuration for deliverywithin a vasculature and an expanded configuration for deployment withina native heart valve. The tubular stent includes a plurality of crownsand a plurality of struts with each crown being formed between a pair ofopposing struts. The plurality of crowns and the plurality of strutsdefine a plurality of openings of the tubular stent and the tubularstent has endmost crowns and endmost openings formed at an inflow endthereof. An interior skirt is coupled to and covers an innercircumferential surface of the tubular stent. A prosthetic valvecomponent is disposed within and secured to the interior skirt. Anexterior skirt is coupled to and covers an outer circumferential surfaceof the tubular stent. The exterior skirt longitudinally extends over atleast the endmost openings of the tubular stent. When the tubular stentis in at least the compressed configuration at least one endmost crownis positioned radially inwards with respect to the remaining endmostcrowns formed at the inflow end of the tubular stent, thereby forming acircumferentially-extending gap between the endmost crowns adjacent tothe at least one endmost crown positioned radially inwards in order toprovide a low profile while accommodating the exterior skirt.

According to another embodiment hereof, a transcatheter valve prosthesisincludes a tubular stent having a compressed configuration for deliverywithin a vasculature and an expanded configuration for deployment withina native heart valve. A skirt is coupled to the tubular stent, with afirst portion of the skirt being attached to and covering an innercircumferential surface of the tubular stent and a second portion of theskirt being attached to and covering an outer circumferential surface ofan inflow end of the tubular stent. The skirt is continuous from thefirst portion to the second portion such that the first and secondportions do not overlap. A prosthetic valve component is disposed withinand secured to the first portion of the skirt.

BRIEF DESCRIPTION OF DRAWINGS

The foregoing and other features and advantages of the invention will beapparent from the following description of embodiments hereof asillustrated in the accompanying drawings. The accompanying drawings,which are incorporated herein and form a part of the specification,further serve to explain the principles of the invention and to enable aperson skilled in the pertinent art to make and use the invention. Thedrawings are not to scale.

FIG. 1 is a side view illustration of an exemplary or knowntranscatheter valve prosthesis for use in embodiments hereof.

FIG. 2 is a top view illustration of the transcatheter valve prosthesisof FIG. 1.

FIG. 3 is a side view illustration of the transcatheter valve prosthesisof FIG. 1 implanted within a native valve annulus.

FIG. 4 is a side view illustration of a transcatheter valve prosthesisincluding a first or interior skirt around an inner surface thereof anda second or exterior skirt around an outer surface thereof, thetranscatheter valve prosthesis being shown in a deployed or expandedconfiguration, wherein at least one endmost crown of the transcathetervalve prosthesis is positioned radially inward in order to accommodatethe exterior skirt when the transcatheter valve prosthesis is in acompressed or delivery configuration and wherein the interior skirt andexterior skirt are formed from the same material.

FIG. 4A is a cross-sectional view of a strut of the transcatheter valveprosthesis of FIG. 4 taken along line A-A of FIG. 4.

FIG. 4B is a side view illustration of an alternative configuration of astent profile for use in embodiments hereof.

FIG. 4C is a side view illustration of an alternative configuration of astent profile for use in embodiments hereof.

FIG. 4D is a side view of a single side opening of the stent of thetranscatheter valve prosthesis of FIG. 4.

FIG. 5 is a side view illustration of a transcatheter valve prosthesisincluding an interior skirt around an inner surface thereof and anexterior skirt around an outer surface thereof according to anotherembodiment hereof, the transcatheter valve prosthesis being shown in adeployed or expanded configuration, wherein the interior skirt andexterior skirt are formed from different materials.

FIG. 6 is an end view of an inflow end of the transcatheter valveprosthesis of FIG. 4, wherein the transcatheter valve prosthesis is in acompressed or delivery configuration and disposed within a deliverysheath.

FIG. 7 is an end view of an inflow end of the transcatheter valveprosthesis of FIG. 4, wherein the transcatheter valve prosthesis is in adeployed or expanded configuration.

FIG. 8 is a side view illustration of a transcatheter valve prosthesisincluding a skirt attached to a tubular stent thereof, the transcathetervalve prosthesis being shown in a deployed or expanded configuration,wherein a first or interior portion of the skirt extends around an innersurface of the stent and a second or exterior portion of the skirtextends around an outer surface of the stent.

FIG. 9 illustrates a portion of the skirt of FIG. 8 removed from thetranscatheter valve prosthesis and laid flat for illustrative purposesonly.

FIG. 10 is an enlarged side view illustration of an inflow end of thetranscatheter valve prosthesis of FIG. 8.

FIG. 10A is an enlarged side view illustration of a portion of an inflowend of the transcatheter valve prosthesis of FIG. 8.

FIG. 11 is a side view of a single endmost side opening of the stent ofthe transcatheter valve prosthesis of FIG. 8.

DETAILED DESCRIPTION OF THE INVENTION

Specific embodiments of the present invention are now described withreference to the figures, wherein like reference numbers indicateidentical or functionally similar elements. If utilized herein, theterms “distal” or “distally” refer to a position or in a direction awayfrom the heart and the terms “proximal” and “proximally” refer to aposition near or in a direction toward the heart. The following detaileddescription is merely exemplary in nature and is not intended to limitthe invention or the application and uses of the invention. Although thedescription of the invention is in the context of treatment of heartvalves, the invention may also be used where it is deemed useful inother valved intraluminal sites that are not in the heart. For example,the present invention may be applied to venous valves as well.Furthermore, there is no intention to be bound by any expressed orimplied theory presented in the preceding technical field, background,brief summary or the following detailed description.

FIG. 1 depicts an exemplary transcatheter valve prosthesis 100.Transcatheter valve prosthesis 100 is illustrated herein in order tofacilitate description of components attached thereto and/or integratedthereon for preventing and/or repairing paravalvular leakage accordingto embodiments hereof. It is understood that any number of alternateheart valve prostheses can be used with the components for preventingand/or repairing paravalvular leakage described herein. Transcathetervalve prosthesis 100 is merely exemplary and is described in more detailin U.S. Patent Application Pub. No. 2011/0172765 to Nguyen et al., whichis incorporated by reference herein in its entirety.

Transcatheter valve prosthesis 100 includes an expandable stent or frame102 that supports a prosthetic valve component including one or morevalve leaflets 104 within the interior of stent 102. The prostheticvalve component is capable of blocking flow in one direction to regulateflow there-through via valve leaflets 104 that may form a bicuspid ortricuspid replacement valve. Valve leaflets 104 are attached to aninterior skirt or graft material 106 which encloses or lines a portionof stent 102 as would be known to one of ordinary skill in the art ofprosthetic tissue valve construction. Valve leaflets 104 are sutured orotherwise securely and sealingly attached along their bases 110 to theinterior surface of interior skirt 106. Adjoining pairs of leaflets areattached to one another at their lateral ends to form commissures 120,with free edges 122 of the leaflets forming coaptation edges that meetin area of coaptation 114. FIG. 2 is an end view of FIG. 1 andillustrates an exemplary tricuspid valve having three leaflets 104,although a bicuspid leaflet configuration may alternatively be used inembodiments hereof. More particularly, if transcatheter valve prosthesis100 is configured for placement within a native valve having threeleaflets such as the aortic, tricuspid, or pulmonary valves,transcatheter valve prosthesis 100 includes three valve leaflets 104. Iftranscatheter valve prosthesis 100 is configured for placement within anative valve having two leaflets such as the mitral valve, transcathetervalve prosthesis 100 includes two valve leaflets 104.

Leaflets 104 may be made of pericardial material; however, the leafletsmay instead be made of another material. Natural tissue for replacementvalve leaflets may be obtained from, for example, heart valves, aorticroots, aortic walls, aortic leaflets, pericardial tissue, such aspericardial patches, bypass grafts, blood vessels, intestinal submucosaltissue, umbilical tissue and the like from humans or animals. Syntheticmaterials suitable for use as leaflets 104 include DACRON® polyestercommercially available from Invista North America S.A.R.L. ofWilmington, Del., other cloth materials, nylon blends, polymericmaterials, and vacuum deposition nitinol fabricated materials. Onepolymeric material from which the leaflets can be made is an ultra-highmolecular weight polyethylene material commercially available under thetrade designation DYNEEMA from Royal DSM of the Netherlands. Withcertain leaflet materials, it may be desirable to coat one or both sidesof the leaflet with a material that will prevent or minimize overgrowth.It is further desirable that the leaflet material is durable and notsubject to stretching, deforming, or fatigue.

Delivery of transcatheter valve prosthesis 100 may be accomplished via apercutaneous transfemoral approach or a transapical approach directlythrough the apex of the heart via a thoracotomy, or may be positionedwithin the desired area of the heart via different delivery methodsknown in the art for accessing heart valves. During delivery, ifself-expanding, the prosthetic valve remains compressed until it reachesa target diseased native heart valve, at which time transcatheter valveprosthesis 100 can be released from the delivery catheter and permittedto expand in situ via self-expansion. The delivery catheter is thenremoved and transcatheter valve prosthesis 100 remains deployed withinthe native target heart valve. Alternatively, transcatheter valveprosthesis 100 may be balloon-expandable and delivery thereof may beaccomplished via a balloon catheter as would be understood by one ofordinary skill in the art.

FIG. 3 is a side view illustration of transcatheter valve prosthesis 100implanted within a native aortic heart valve, which is shown in section,having native leaflets L_(N) and corresponding native sinuses S_(N).When transcatheter valve prosthesis 100 is deployed within the valveannulus of a native heart valve, stent 102 is configured to be expandedwithin native valve leaflets L_(N) of the patient's defective valve, tothereby retain the native valve leaflets in a permanently open state.The native valve annulus may include surface irregularities on the innersurface thereof, and as a result one or more gaps or cavities/crevices326 may be present or may form between the perimeter of transcathetervalve prosthesis 100 and the native valve annulus. For example, calciumdeposits may be present on the native valve leaflets (e.g., stenoticvalve leaflets) and/or shape differences may be present between thenative heart valve annulus and prosthesis 100. More particularly, insome cases native annuli are not perfectly rounded and have indentationscorresponding to the commissural points of the native valve leaflets. Asa result, a prosthesis having an approximately circular cross-sectiondoes not provide an exact fit in a native valve. These surfaceirregularities, whatever their underlying cause, can make it difficultfor conventional prosthetic valves to form a blood tight seal betweenthe prosthetic valve and the inner surface of the valve annulus, causingundesirable paravalvular leakage and/or regurgitation at theimplantation site.

Embodiments hereof relate to a transcatheter valve prosthesis having anexterior skirt that encircles or surrounds an outer surface of thetranscatheter valve prosthesis in order to occlude or fill gaps betweenthe perimeter of a transcatheter valve prosthesis and the native valveannulus, thereby reducing, minimizing, or eliminating leaksthere-between. More particularly, with reference to FIG. 4, a side viewof a transcatheter valve prosthesis 400 is shown in its expanded ordeployed configuration. Similar to transcatheter valve prosthesis 100,transcatheter valve prosthesis 400 includes a tubular stent 402, aninterior skirt 406 coupled to and covering an inner circumferentialsurface of stent 402, and a prosthetic valve component that includesleaflets 404 disposed within and secured to interior skirt 406. However,unlike transcatheter valve prosthesis 100, transcatheter valveprosthesis 400 also includes exterior skirt 434 coupled to and coveringan outer circumferential surface of stent 402 for sealing and preventingparavalvular leakage. Exterior skirt 434 functions to block anyretrograde flow within the native valve, thereby preventing undesiredregurgitation and preventing blood stagnation in and around the nativevalve sinuses. In addition, when transcatheter valve prosthesis 400 isdeployed, exterior skirt 434 fills any/all gaps or cavities/crevicesbetween the outer surface of stent 402 and native valve tissue such thatblood flow through the target gap or cavity is occluded or blocked, orstated another way blood is not permitted to flow there-through.Exterior skirt 434 functions as a continuous circumferential seal aroundtranscatheter valve prosthesis 400 to block or prevent blood flow aroundthe outer perimeter of the prosthesis, thereby minimizing and/oreliminating any paravalvular leakage at the implantation site.

Conventionally when additional exterior skirt material is added to atranscatheter valve prosthesis, some portions of a self-expanding stentmay be inadvertently pushed or displaced radially inward when thetranscatheter valve prosthesis is compressed or contracted into a sheathfor delivery. More particularly, when a transcatheter valve prosthesiswithout an exterior skirt, such as transcatheter valve prosthesis 100described above, is compressed or contracted into a sheath of a deliverycatheter, the struts of stent 102 are compressed to abut against eachtogether in order to fit into the sheath and the outer surface of eachstrut presses against the inner surface of the sheath. The material ofinterior skirt 106 compresses or packs into the lumen of stent 102.However, when an exterior skirt is added to a transcatheter valveprosthesis, the extra material may cause a portion of the stent to bepushed inwardly and any portions of the stent that are pushed inwardlyno longer press against the inner surface of the sheath of the deliverycatheter. With the addition of an exterior skirt and no furthermodifications to either the valve prosthesis or the delivery system,such as using a delivery system with a wider lumen diameter and also agreater delivery profile, the delivery configuration is unpredictableand may lead to erratic loading forces, deployment forces, and/orrecapture forces. In order to accommodate the addition of exterior skirt434, stent 402 is formed such that at least one endmost crown thereof ispositioned radially inwards with respect to the remaining endmost crownsas will be described in more detail herein.

Stent 402 will now be described in more detail. Stent 402 of valveprosthesis 400 has a deployed configuration including an enlarged orflared first end 416 and a second end 418. In the embodiment depicted inFIG. 4, valve prosthesis 400 is configured for replacement for an aorticvalve such that second end 418 functions as an inflow or distal end oftranscatheter valve prosthesis 400 and extends into and anchors withinthe aortic annulus of a patient's left ventricle, while first end 416functions as an outflow or proximal end of transcatheter valveprosthesis 400 and is positioned in the patient's ascending aorta. Asalternatives to the deployed configuration of FIG. 4, the stent/valvesupport frame may have an hourglass configuration or profile 402B shownin FIG. 4B, a generally tubular configuration or profile 402C as shownin FIG. 4C, or other stent configuration or shape known in the art forvalve replacement.

Stent 402 is a unitary tubular component having a plurality of sideopenings 432, which may be formed by a laser-cut manufacturing methodand/or another conventional stent forming method as would be understoodby one of ordinary skill in the art. In an embodiment, side openings 432may be diamond-shaped or of another shape. Stent 402 includes aplurality of crowns 430 and a plurality of struts 428 with each crownbeing formed between a pair of opposing struts. Each crown 430 is acurved segment or bend extending between opposing struts 428. Theplurality of crowns 430 and the plurality of struts 428 define theplurality of side openings 432 of the tubular stent 402. Moreparticularly, as best shown in FIG. 4D which is a side view of a singleside opening 432 of stent 402, each side opening 432 is formed by twopairs of opposing crowns 430 and four struts 428 therebetween. Stent 402has endmost side openings 432A including endmost crowns 430A at inflowor distal end 418 thereof. For sake of clarity, the two strutsimmediately adjacent to each endmost crown 430A are herein referred toas endmost struts 428A. It will be understood by one of ordinary skillin the art that the illustrated configurations of stent 402 areexemplary and stent 402 may have alternative patterns or configurations.For example, in another embodiment (not shown), stent 402 may include aseries of independent or separate sinusoidal patterned rings coupled toeach other to form a tubular component.

With reference to FIG. 4A, in an embodiment hereof, stent 402 is lasercut from a cylindrical tube and the cross-sectional shape of struts 428and crowns 430, including endmost struts 428A and endmost crowns 430A,are trapezoidal with a shorter face or surface 480 of the trapezoidforming the inner surface of the strut/crown and a longer face orsurface 482 of the trapezoid forming the outer surface of thestrut/crown. When stent 402 is compressed for delivery, adjacent strutsand crowns abut or are pressed together and the mating surfaces thereofaid to prevent any struts or crowns being inadvertently pushed forward.

In embodiments hereof, stent 402 is self-expanding to return to anexpanded deployed state from a compressed or constricted delivery stateand may be made from stainless steel, a pseudo-elastic metal such as anickel titanium alloy or Nitinol, or a so-called super alloy, which mayhave a base metal of nickel, cobalt, chromium, or other metal.“Self-expanding” as used herein means that a structure/component has amechanical memory to return to the expanded or deployed configuration.Mechanical memory may be imparted to the wire or tubular structure thatforms stent 402 by thermal treatment to achieve a spring temper instainless steel, for example, or to set a shape memory in a susceptiblemetal alloy, such as nitinol, or a polymer, such as any of the polymersdisclosed in U.S. Pat. Appl. Pub. No. 2004/0111111 to Lin, which isincorporated by reference herein in its entirety. Alternatively,transcatheter valve prosthesis 400 may be made balloon-expandable aswould be understood by one of ordinary skill in the art.

Exterior skirt 434 is coupled to the outer surface of transcathetervalve prosthesis 400 around inflow or distal end 418 thereof. Exteriorskirt 434 may be attached to stent 402 by any suitable means known tothose skilled in the art, for example and not by way of limitation,suture/stitches, welding, adhesive, or mechanical coupling. In anembodiment, stitches 435 surround or extend around the perimeter of eachendmost side opening 432A in order to fully secure and fix exteriorskirt 434 to the outer surface of transcatheter valve prosthesis 400.When deployed, exterior skirt 434 may be positioned in situ at thenative valve annulus, slightly above the valve annulus, slightly belowthe valve annulus, or some combination thereof. Since the exterior skirtis coupled to the outer surface of transcatheter valve prosthesis 400,longitudinal placement and/or the size and shape thereof may be adjustedor adapted according to each application and to a patient's uniqueneeds. For example, depending on the anatomy of the particular patient,the exterior skirt may be positioned on transcatheter valve prosthesis400 so that in situ the exterior skirt is positioned betweentranscatheter valve prosthesis 400 and the interior surfaces of thenative valve leaflets, between transcatheter valve prosthesis 400 andthe interior surfaces of the native valve annulus, and/or betweentranscatheter valve prosthesis 400 and the interior surfaces of the leftventricular outflow track (LVOT).

Exterior skirt 434 longitudinally extends over at least endmost sideopenings 432A of stent 402 but the length of exterior skirt 434 may varyaccording to application. In an embodiment hereof, as shown in FIG. 4,exterior skirt 434 longitudinally extends over only endmost sideopenings 432A of stent 402. However, exterior skirt 434 may extend overa longer portion of transcatheter valve prosthesis 400. In anotherembodiment hereof (not shown), exterior skirt 434 may extend up to bases410 of leaflets 406. In another embodiment hereof (not shown), exteriorskirt 434 may extend to an intermediate position between bases 410 ofleaflets 406 and endmost side openings 432A.

Interior skirt 406 is coupled to the inner surface of transcathetervalve prosthesis 400. In the embodiment of FIG. 4, interior skirt 406longitudinally extends from bases 410 of leaflets 406 to inflow ordistal end 418 of transcatheter valve prosthesis 400. As such, in theembodiment of FIG. 4, double layers of skirt material, i.e., a firstlayer via exterior skirt 434 and a second layer via interior skirt 406,extend over endmost side openings 432A of stent 402. The layers of skirtmaterial, i.e., a first layer via exterior skirt 434 and a second layervia interior skirt 406, overlap or overlay each other around inflow end418 of valve prosthesis 400. Inflow end 418 is thus sandwiched orpositioned between layers of skirt material. However, the length ofinterior skirt 406 may vary according to application and interior skirt406 may extend over a shorter portion of transcatheter valve prosthesis400. In another embodiment hereof (not shown), interior skirt 406 maylongitudinally extend from bases 410 of leaflets 406 to a proximal endor edge of exterior skirt 434 such that the layers of skirt material donot overlap or overlay each other.

Although exterior and interior skirts 434, 406 are described herein asseparate or individual components with exterior skirt 434 being coupledto an outer surface of stent 402 and interior skirt 406 being coupled toan inner surface of stent 402, in another embodiment hereof (not shown)the skirts may be formed from the same or single component. For example,exterior and interior skirts 434, 406 may be formed via a single foldedcomponent that is coupled to both the inner and outer surfaces of stent402 with the fold thereof extending over or around inflow or distal end418 of valve prosthesis 400.

In the embodiment of FIG. 4, exterior and interior skirts 434, 406,respectively, are formed from the same material. Exterior and interiorskirts 434, 406, respectively, may be a natural or biological materialsuch as pericardium or another membranous tissue such as intestinalsubmucosa. Alternatively, exterior and interior skirts 434, 406,respectively, may be a low-porosity woven fabric, such as polyester,Dacron fabric, or PTFE, which creates a one-way fluid passage whenattached to the stent. In one embodiment, exterior and interior skirts434, 406, respectively, may be a knit or woven polyester, such as apolyester or PTFE knit, which can be utilized when it is desired toprovide a medium for tissue ingrowth and the ability for the fabric tostretch to conform to a curved surface. Polyester velour fabrics mayalternatively be used, such as when it is desired to provide a mediumfor tissue ingrowth on one side and a smooth surface on the other side.These and other appropriate cardiovascular fabrics are commerciallyavailable from Bard Peripheral Vascular, Inc. of Tempe, Ariz., forexample. Elastomeric materials such as but not limited to polyurethanemay also be used as a material for exterior and interior skirts 434,406. In another embodiment hereof, as shown in FIG. 5, exterior andinterior skirts 534, 506, respectively, of a transcatheter valveprosthesis 500 are formed from different materials. In the embodiment ofFIG. 5, for example, exterior skirt 534 is formed from a fabric materialsuch as those listed above and interior skirt 506 is formed from anatural or biological material such as those listed above. Differentmaterial combinations for the exterior and interior skirts may varyaccording to application.

Stent 402 has a compressed configuration for delivery within avasculature as shown in FIG. 6 and an expanded configuration fordeployment within a native heart valve as shown in FIG. 7. FIG. 6 is anend view of inflow or distal end 418 of transcatheter valve prosthesis400, with transcatheter valve prosthesis 400 compressed or contractedinto a delivery sheath 640 of a delivery system or catheter. Aspreviously mentioned, in order to provide a low profile yet stillaccommodate exterior skirt 434, at least one endmost crown 430A_(I) oftranscatheter valve prosthesis 400 is positioned radially inwards or isradially offset with respect to the remaining endmost crowns 430A formedat inflow end 418 of stent 402. For sake of clarity, endmost crowns thatare positioned radially inwards are herein referred to as offset endmostcrowns 430A_(I). By relocating at least one offset endmost crown430A_(I) radially inward, a circumferentially-extending gap 638 (shownon FIG. 6) is formed or created between the endmost crowns 430A adjacentto the at least one offset endmost crown 430A_(I) in order toaccommodate the material of exterior skirt 434.“Circumferentially-extending gap” as used herein refers to a gap orspace that extends in a circumferential direction between two endmostcrowns 430 that are directly adjacent to or next to an offset endmostcrown 430A_(I).

In the embodiment of FIG. 6, every third endmost crown is positionedradially inwards with respect to the remaining endmost crowns in orderto accommodate exterior skirt 434. The remaining endmost crowns 430A arecompressed together in order to fit within delivery sheath 640 and theouter surface of each remaining endmost crown 430A presses against theinner surface of delivery sheath 640. Exterior skirt 434 is sandwichedbetween the inner surface of delivery sheath 640 and the outer surfaceof stent 402, while interior skirt 406 compresses or packs within thelumen of stent 402 and does not interfere with stent 402. By configuringoffset endmost crowns 430A_(I) to be positioned radially inward, thedelivery configuration of transcatheter valve prosthesis 400 ispredictable and organized, thereby leading to relatively lower andpredictable loading forces, deployment forces, and/or recapture forces.The number of offset endmost crowns may vary according to application.Although FIG. 6 illustrates every third endmost crown being positionedradially inwards with respect to the remaining endmost crowns, only oneendmost crown is required to be positioned radially inwards in order toaccommodate exterior skirt 434. Other embodiments hereof may includeevery fourth endmost crown being positioned radially inwards withrespect to the remaining endmost crowns or may include every otherendmost crown being positioned radially inwards with respect to theremaining endmost crowns. Although deemed most beneficial in atranscatheter valve prosthesis such as transcatheter valve prosthesis400 having a double layer of skirt material extending over at least aportion of the endmost side openings of the stent, positioning one ormore endmost crowns radially inwards with respect to the remainingendmost crowns may be utilized on any transcatheter prostheses having anexterior skirt in order to accommodate the exterior skirt material andensure that the delivery configuration of the transcatheter valveprosthesis is predictable and organized.

In order to configure offset endmost crowns 430A_(I) of transcathetervalve prosthesis 400 to be positioned radially inwards with respect tothe remaining endmost crowns 430A formed at inflow end 418 of stent 402,stent 402 is formed in the expanded or deployed configuration shown inFIG. 7. FIG. 7 is an end view of inflow or distal end 418 oftranscatheter valve prosthesis 400, and every third endmost crown ispositioned radially inwards with respect to the remaining endmost crownsas shown. In this embodiment, when stent 402 is in the expandedconfiguration, each offset endmost crown 430A_(I) is positioned radiallyinwards a predetermined distance D (shown in phantom in FIG. 7) of 1millimeter relative to the radial position of the remaining endmostcrowns 430A. In order to position an offset endmost crown 430A_(I)radially inwards, at least endmost struts 428A that are immediatelyadjacent to the offset endmost crown 430A_(I) bend radially inwards.More particularly, endmost struts 428A that meet at or are directlyassociated with the offset endmost crown 430A_(I) are heat set or shapeset to bend towards the center of stent 402 to position the offsetendmost crown 430A_(I) radially inwards by a predetermined distance.“Radially inwards” as used herein includes positioning a selected orparticular crown a predetermined distance closer to or towards thecenter of the transcatheter valve prosthesis. However, as will beunderstood by one of ordinary skill in the art, the predetermineddistance may vary according to application and thus in anotherembodiment hereof, the offset endmost crowns 430A_(I) may be positionedradially inwards a predetermined distance of between 0.5 and 1.5millimeters relative to the radial position of the remaining endmostcrowns 430A. When transcatheter valve prosthesis 400 is compressed orcontracted for delivery, the spacial relationship of each endmost crownrelative to the center of the transcatheter valve prosthesis holds or ismaintained such that transcatheter valve prosthesis 400 has thecompressed or delivery configuration shown in FIG. 6 in which everythird endmost crown is positioned radially inwards with respect to theremaining endmost crowns. In another embodiment hereof (not shown),struts and crowns proximal to endmost struts 428A may also be heat setor shape set to bend towards a center line or longitudinal axis of stent402 such that the offset endmost crown 430A_(I) is positioned radiallyinwards by a predetermined distance. For example, in another embodimenthereof, the struts and crowns that form a side opening adjacent tooffset endmost crown 430A_(I) may be heat set or shape set to bendtowards a center line or longitudinal axis of stent 402 in order toposition offset endmost crown 430A_(I) radially inwards.

In another embodiment hereof, in addition to and/or as an alternative topositioning at least one endmost crown radially inward in order toaccommodate an exterior skirt, a single layer skirt that passes throughor traverses the stent may be utilized. Stated another way, in order toavoid a double layer of skirt material at the inflow end of thetranscatheter valve prosthesis, another embodiment hereof is related toa single skirt component that includes an interior portion and anexterior portion. Since the first and second portions of the skirt donot overlap, only a single layer of skirt material covers either aninner surface or outer surface of the stent and thus there is sufficientroom for the stent struts to be compressed together and packed into thedelivery sheath without inadvertently pushing any struts/crowns radiallyinward.

More particularly, with reference to FIG. 8, a side view of atranscatheter valve prosthesis 800 having a first end 816 and a secondend 818 is shown. Valve prosthesis 800 is configured for replacement foran aortic valve such that second end 818 functions as an inflow ordistal end thereof and extends into and anchors within the aorticannulus of a patient's left ventricle, while first end 816 functions asan outflow or proximal end of transcatheter valve prosthesis 800 and ispositioned in the patient's ascending aorta. Similar to transcathetervalve prosthesis 100, transcatheter valve prosthesis 800 includes atubular stent 802, a skirt 850, and a prosthetic valve component thatincludes leaflets 804 disposed within stent 802. However, while skirt106 of transcatheter valve prosthesis 100 is solely interior andencloses or lines the inner surface of stent 102, skirt 850 oftranscatheter valve prosthesis 800 is a single component that includes afirst or interior portion 850A attached to and covering an innercircumferential surface of stent 802 and a second or exterior portion850B attached to and covering an outer circumferential surface of aninflow end 818 of stent 802. As will be explained in more detail herein,interior and exterior portions 850A, 850B of skirt 850 do not overlapsuch that only a single layer of skirt material covers the stent at anylongitudinal position thereof. Although described separately forillustrative purposes herein, it will be understood by one of ordinaryskill in the art that interior and exterior portions 850A, 850B of skirt850 are continuous, integral sections or portions of a single component,i.e., skirt 850. The interior and exterior portions of skirt 850A arenon-overlapping such that no portion of stent 802 is sandwiched orpositioned between layers of skirt material. In an embodiment, skirt 850is a one-piece component and has no seams thereon or there-through priorto assembly onto stent 802. The prosthetic valve component that includesleaflets 804 is disposed within and secured to interior portion 850A ofskirt 850, and exterior portion 850B of skirt 850 functions to block anyretrograde flow within the native valve, thereby preventing undesiredregurgitation and preventing blood stagnation in and around the nativevalve sinuses. In addition, when transcatheter valve prosthesis 800 isdeployed, exterior portion 850B of skirt 850 is configured tosubstantially fill any/all gaps or cavities/crevices between the outersurface of stent 802 and native valve tissue. Exterior portion 850B ofskirt 850 functions as a continuous circumferential seal aroundtranscatheter valve prosthesis 800 to block or prevent blood flow aroundthe outer perimeter of the prosthesis, thereby minimizing and/oreliminating any paravalvular leakage at the implantation site.

Similar to previous embodiments described above, stent 802 includes aplurality of crowns 830 and a plurality of struts 828 with each crownbeing formed between a pair of opposing struts. The plurality of crowns830 and the plurality of struts 828 define a plurality of side openings832 of the tubular stent 802 as described above with respect to FIG. 4.Stent 802 has endmost side openings 832A at inflow or distal end 818thereof. With additional reference to FIG. 11, which is a side view of asingle endmost side opening 832A of stent 802, each endmost side opening832A is formed via two pairs of opposing crowns 830, with one crownbeing an endmost crown 830A, and four struts therebetween. For sake ofillustration, the struts immediately adjacent to endmost crown 830A areherein referred to as endmost struts 828A and the remaining two strutsof each endmost side opening 832A are herein referred to as a securedstrut 828 _(S) and an overpassed strut 828 _(O). As will be explained inmore detail, although the struts themselves are similar structureshaving similar configurations, secured strut 828 _(S) and overpassedstrut 828 _(O) are herein differentiated from each other due to theirrespective roles during attachment of exterior portion 850B of skirt 850thereto.

Exterior portion 850B of skirt 850 longitudinally extends over or coversat least endmost side openings 832A of stent 802. In an embodimenthereof, as shown in FIG. 8, exterior portion 850B of skirt 850longitudinally extends over or covers only endmost side openings 832A ofstent 802. However, exterior portion 850B of skirt 850 may extend over alonger portion of transcatheter valve prosthesis 800 such as but notlimited to two or more rows of side openings at inflow or distal end 818thereof. Interior portion 850A of skirt 850 longitudinally extends froma proximal end or edge of exterior portion 850B of skirt 850 up to bases810 of leaflets 806. As such, in this embodiment, only a single layer ofskirt material, i.e., exterior portion 850B of skirt 850, extends overinflow or distal end 818 of stent 802. Skirt 850 may be a natural orbiological material such as pericardium or another membranous tissuesuch as intestinal submucosa. Alternatively, skirt 850 may be alow-porosity woven fabric, such as polyester, Dacron fabric, or PTFE,which creates a one-way fluid passage when attached to the stent. In oneembodiment, skirt 850 may be a knit or woven polyester, such as apolyester or PTFE knit, which can be utilized when it is desired toprovide a medium for tissue ingrowth and the ability for the fabric tostretch to conform to a curved surface. Polyester velour fabrics mayalternatively be used, such as when it is desired to provide a mediumfor tissue ingrowth on one side and a smooth surface on the other side.These and other appropriate cardiovascular fabrics are commerciallyavailable from Bard Peripheral Vascular, Inc. of Tempe, Ariz., forexample. Elastomeric materials such as but not limited to polyurethanemay also be used as a material for skirt 850.

In order for skirt 850 to pass through or transverse stent 802, skirt850 includes a plurality of cuts 852 therein that are positioned topermit exterior portion 850B of skirt 850 to extend from the innersurface to the outer surface of stent 802 through certain side openings832 thereof. More particularly, FIG. 9 illustrates a portion of skirt850 removed from transcatheter valve prosthesis 800 and laid flat forillustrative purposes only. Skirt 850 includes a proximal end 853 havinga triangular edge 859 that corresponds to or substantially matches theshape of bases 810 of leaflets 804 and a distal end 856 having asinusoidal or wavy edge 857 with alternating peaks and valleys thatcorresponds to or substantially matches the shape of inflow or distalend 818 of stent 802. In an embodiment hereof, each cut 852 stems from avalley of wavy edge 857 at an angle ⊖ relative to a longitudinal axisL_(A) of transcatheter valve prosthesis 800 which may range between 0and 60 degrees, depending upon the geometry of the struts of stent 802.Further, each cut 852 may have a length between 2 mm to 3 cm, dependingupon the geometry of the struts of stent 802, and in an embodiment, thelength of each cut 852 is equal to the length of secured strut 828 _(S)of endmost side opening 832A. The plurality of cuts 852 create or form aplurality of individual portions or flaps 858 therebetween such that asingle flap is created between two adjacent cuts, with each flap 858longitudinally extending from the proximal ends of cuts 852 to the wavyedge 857 of skirt 850. Each cut 852 forms a first edge 862 on skirt 850and a second or opposing edge 864 on skirt 850, with first edge 862being disposed on material that forms interior portion 850A of skirt 850and second edge 864 being disposed on material that forms exteriorportion 850B of skirt 850 as will be explained in more detail hereinwith respect to FIG. 10A.

With additional reference to FIG. 10 and FIG. 10A, when being placed orassembled onto stent 802, skirt 850 is positioned on the inner surfaceof the stent and interior portion 850A of skirt 850 is coupled theretowith a plurality of stitches 860. Interior portion 850A of skirt 850includes proximal end 853 of skirt 850 and extends to a proximal end ofthe plurality of cuts 852. Exterior portion 850B is then positioned ontothe outer surface of stent 802. More particularly, each flap 858 ofexterior portion 850B of skirt 850 is passed or directed through arespective side opening 832 (that is adjacent to an endmost side opening832A to be covered by the flap 858 of exterior portion 850B of skirt850) of stent 802 and over an overpassed or covered strut 828 ₀ (shownin phantom on FIG. 10) of the endmost side opening 832A as indicated bydirectional arrows 855 shown on FIG. 10 and herein referred to asoverpass or transition zones 854 shown on FIG. 10. Once flaps 858 are onthe outer surface of the stent, flaps 858 extend over endmost sideopenings 832A with the plurality of cuts 852 positioned adjacent tosecured struts 828 _(S) of endmost side openings 832A.

Flaps 858 of exterior portion 850B of skirt 850 are then secured orattached to stent 802 such that each flap 858 sealingly covers orextends over an endmost side opening 832A of stent 802. Moreparticularly, each flap 858 is sewn to three struts, i.e., both ofendmost struts 828A and secured strut 828 _(S), of each endmost sideopening 832A. Notably, exterior portion 850B of skirt 850 extends orpasses over the fourth strut of each endmost side opening 832A, i.e.,overpassed strut 828 ₀, but is not attached or sewn to overpassed strut828 ₀. Stated another way, there is no seam at overpass zones 854 inwhich skirt 850 passes or flows from an inner surface of stent 802 to anouter surface of stent 802. Rather, at overpass zones 854 as shown onFIG. 10, the material of skirt 850 passes or extends over overpassedstruts 828 _(O) of endmost side openings 832A of stent 802 in order tomaintain valvular sealing at overpass zones 854. The amount of materialis minimized when skirt 850 passes or flows from an inner surface ofstent 802 to an outer surface of stent 802.

In addition, as best shown on FIG. 10A, when flaps 858 are positionedover endmost side openings 832A, the plurality of cuts 852 arepositioned adjacent to secured struts 828 _(S) of endmost side opening832 of stent 802. Interior portion 850A of skirt 850 have first edges862 of cuts 852 and exterior portions 850B of skirt 850 have secondedges 864 of cuts 852, with secured struts 828 _(S) being sandwiched orpositioned between edges 862, 864 of interior, exterior portions 850A,850B, respectively, of skirt 850. Although secured struts 828 _(S) aresandwiched between edges 862, 864 of interior, exterior portions 850A,850B, respectively, of skirt 850, edges 862, 864 do not overlap oroverlay. A single seam or row 861 of stitches 860 is utilized to coupleor attach each secured struts 828 _(S) to both edges 862, 864 ofinterior, exterior portions 850A, 850B, respectively, of skirt 850.Since no portions of interior and exterior portions 850A, 850B of skirt850 overlap or overlay each other, only a single layer of skirt materialextends over stent 802 in order to minimize the amount of material andprofile of the transcatheter valve prosthesis. Skirt 850 advantageouslyprovides interior portion 850A for securement of leaflets 804 as well asexterior portion 850B for improved sealing, while avoiding a doublelayer of skirt material in order to minimize the profile of thetranscatheter valve prosthesis.

Although not required, transcatheter valve prosthesis 800 may alsoinclude one or more endmost crowns that are positioned radially inwardswith respect to the remaining endmost crowns in order to accommodate thematerial of exterior skirt portion 850B and ensure that the deliveryconfiguration of the transcatheter valve prosthesis is predictable andorganized as described above with respect to the embodiments of FIGS. 4,6, and 7. In addition, although embodiments depicted herein illustrateexterior skirts or exterior skirt portions on a transcatheter valveprosthesis configured for implantation within an aortic valve, it wouldbe obvious to one of ordinary skill in the art that the exterior skirtsor exterior skirt portions as described herein may be integrated onto atranscatheter valve prosthesis configured for implantation within otherheart valves, such as a mitral valve or a pulmonary valve. Thetranscatheter valve prosthesis may be designed with a number ofdifferent configurations and sizes to meet the different requirements ofthe location in which it may be implanted.

While various embodiments according to the present invention have beendescribed above, it should be understood that they have been presentedby way of illustration and example only, and not limitation. It will beapparent to persons skilled in the relevant art that various changes inform and detail can be made therein without departing from the spiritand scope of the invention. Thus, the breadth and scope of the presentinvention should not be limited by any of the above-described exemplaryembodiments, but should be defined only in accordance with the appendedclaims and their equivalents. It will also be understood that eachfeature of each embodiment discussed herein, and of each reference citedherein, can be used in combination with the features of any otherembodiment. All patents and publications discussed herein areincorporated by reference herein in their entirety.

1. A transcatheter valve prosthesis comprising: a tubular stent having acompressed configuration for delivery within a vasculature and anexpanded configuration for deployment within a native heart valve, thetubular stent including a plurality of crowns and a plurality of strutswith each crown being formed between a pair of opposing struts, thetubular stent having endmost crowns formed at an inflow end thereof; askirt coupled to the tubular stent, a first portion of the skirt beingattached to and covering an inner circumferential surface of the tubularstent and a second portion of the skirt being attached to and coveringan outer circumferential surface of an inflow end of the tubular stent,wherein the skirt is continuous from the first portion to the secondportion such that the first and second portions do not overlap; and aprosthetic valve component disposed within and secured to the firstportion of the skirt, wherein when the tubular stent is in at least thecompressed configuration at least one endmost crown is positionedradially inwards with respect to the remaining endmost crowns formed atthe inflow end of the tubular stent.
 2. The transcatheter valveprosthesis of claim 1, wherein when the tubular stent is in the expandedconfiguration the at least one endmost crown is positioned radiallyinwards with respect to the remaining endmost crowns formed at theinflow end of the tubular stent.
 3. The transcatheter valve prosthesisof claim 1, wherein every third endmost crown is positioned radiallyinwards with respect to the remaining endmost crowns formed at theinflow end of the tubular stent.
 4. The transcatheter valve prosthesisof claim 1, wherein the plurality of crowns and the plurality of strutsdefine a plurality of openings of the tubular stent, the tubular stenthaving endmost openings formed at the inflow end thereof, and whereinthe second portion of the skirt extends over only the endmost openingsof the tubular stent.
 5. The transcatheter valve prosthesis of claim 4,wherein the struts that form the endmost opening adjacent to the atleast one endmost crown bend radially inwards in order to position theat least one endmost crown radially inwards with respect to theremaining endmost crowns formed at the inflow end of the tubular stent.6. The transcatheter valve prosthesis of claim 5, wherein the firstportion of the skirt longitudinally extends from a proximal end of thesecond portion of the skirt to the prosthetic valve component. 7-15.(canceled)
 16. A transcatheter valve prosthesis comprising: a tubularstent having a compressed configuration for delivery within avasculature and an expanded configuration for deployment within a nativeheart valve; a skirt coupled to the tubular stent, a first portion ofthe skirt being attached to and covering an inner circumferentialsurface of the tubular stent and a second portion of the skirt beingattached to and covering an outer circumferential surface of an inflowend of the tubular stent, wherein the skirt is continuous from the firstportion to the second portion such that the first and second portions donot overlap; and a prosthetic valve component disposed within andsecured to the first portion of the skirt.
 17. The transcatheter valveprosthesis of claim 16, wherein the tubular stent includes a pluralityof crowns and a plurality of struts with each crown being formed betweena pair of opposing struts, the plurality of crowns and the plurality ofstruts defining a plurality of openings of the tubular stent, andwherein the skirt includes a plurality of cuts therein that arepositioned to permit the second portion of the skirt to extend from theinner surface to the outer surface of the tubular stent through theopenings.
 18. The transcatheter valve prosthesis of claim 16, whereinthe tubular stent has endmost openings formed at the inflow end thereofand wherein the second portion of the skirt longitudinally extends overonly the endmost openings of the tubular stent.
 19. The transcathetervalve prosthesis of claim 18, wherein the first portion of the skirtlongitudinally extends from a proximal end of the second portion of theskirt to the prosthetic valve component.
 20. The transcatheter valveprosthesis of claim 19, wherein each endmost opening includes two pairsof opposing crowns and four struts therebetween and wherein the secondportion of the skirt extends over one strut of each endmost opening andis sewn to the other three struts of each endmost opening.